Optical image intensifiers, e.g. of the microchannel plate type, are well-known and widely used for night vision use. A scene is projected by an optical system onto the input surface of an intensifier tube, and the resulting intensified image on the output surface may be perceived e.g. by an optical microscope system or a TV system. In order to obtain good viewing, the image tube is normally provided with a phosphor layer emitting in a greenish color, corresponding to the maximum light sensitivity of the human eye.
Due to the sensor construction in the human eye, with rods for night vision, void of color sensitivity, and cones for daylight and color vision, it is not generally realized that in fact, a natural scenery has just as much color by night as by day, as long as the available light is multicoloured, which is the case both for moonlight and for starlight, possibly with a different spectral distribution.
It is the general object for the invention to utilize this insight by obtaining a night vision/imaging system which admits of color perception of feebly lit scenes. Besides the obvious military use, such a system would be favorable e.g. for nature viewing and photographing at night or in caverns, hunting, for watchmen and on ships at night.
It is a further object to obtain color vision at night with the use of means which are not too expensive. Although optical image intensifiers nave been improved in recent years, with prices decreasing, they are still expensive and need electrical H.T. equipment, and the invention therefore envisages obtaining color vision using only one image intensifier, which is used in a multiplex system.